Tank for volatile liquids



1938. M. E. cLAwsoN ET AL 2,126,367

TANK FOR VOLATILE LIQUIDS Filed June s, 1936 v\ ll M H INVENTOR.

Q M/flord E 6/0/0500 Patented Aug. 9, 1938 UNITED STATES TANK FOR VOLATILE. LIQUIDS Millard E. Clawson and Frank Mohnk, Ponca City, Okla., assignors to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Application June 5, 1936, Serial No. 83,679

3 Claims.

Our invention relates to tanks for volatile liquids and more particularly to a gas collector head for a casinghead gasoline tank relief valve.

With volatile liquids, as for example, casinghead gasoline, it is diflicult to gauge and investigate the contents of tanks containing them. This is particularly true during the summer months when the temperature of the atmosphere is such as to create relatively high vapor pressure within the tank. Casinghead gasoline, for example, has a vapor pressure of 13 pounds per square inch at F. At F. the vapor pressure rises to about atmospheric or slightly above, namely about 15 pounds per square inch. At F. the vapor pressure is about 18 pounds per square inch, at F. about 21 pounds per square inch and at F. about 25 pounds per square inch. It will be seen that, if the temperature is in the vicinity of 100 F. a vapor pressure of 10 pounds over atmospheric is developed. In order to prevent undue strains being impressed upon tanks containing volatile liquids such as casinghead gasoline, it has been the practice to fit tanks adapted to contain these liquids with relief valves. If these vapors are released to the atmosphere in the case of casinghead gasoline, a distinct fire and explosion hazard is created and the vapors released represent a distinct economic loss.

One object of our invention is to provide a head adapted to collect the gas released from the tank by the relief valve.

Another object of, our invention is to provide means for recovering the vapors released.

Other and further objects of our invention will appear from the following description.

In the accompanying drawing which forms part of the instant specification .and is to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views;

Figure 1 is a diagrammatic view of a tank fitted with apparatus containing one embodiment of our invention.

Figure 2 is a sectional view of a gas collector head.

In general, our invention contemplates providing a chamber into which the vapors, discharged by the relief valve, are adapted to collect. Means are provided for lifting the valve mechanically. We provide means whereby the vapors withdrawn from the gas collector head are absorbed by a liquid absorption menstruum to prevent their loss to the atmosphere.

More particularly referring now to the drawing, a tank I which may be of any suitable construction or design, is fitted with a relief valve 2 which likewise may be of any suitable construction or design. In the drawing, the relief valve 2 is held on seat 3 through the action of the spring 4, acting upon a valve stem 5. Valve stem 5 projects above the valve at 6. A hook I is .adapted to engage any suitable opening in the projection 6. An end of hook I is provided with threads 8 which are adapted to be engaged by a nut 9 provided with an operating handle I0. Normally the pressure of spring 4 is adjusted by nut I I such that it will be sufficient tohold the valve 2 upon its seat through a considerable pressure range. A gas co1- lector head I2 is provided with a gasket I3 and an opening I4. The gasket I3 is adapted to engage an upstanding flange I5 formed upon the valve body I6. The opening I4 permits the threaded portion of the hook 'I to project through the gas collector head I 2. A nipple 20 communicates with the interior of the gas collector head I2 and is threaded at 2| to receive a pipe 22. The pipe 22 communicates with an ejector device 23. A suitable reservoir 24 is provided for the storage of gasoline, light oil or the like. A pump 25 is adapted to take suction from reservoir 24 through a pipe 26 and discharge through pipe 21 to the ejector.

In operation, let us suppose that it is desired to gauge the contents of. tank I. Usually a gauging opening 30 provided with a suitable cover plate 3I is formed in the tank. If the cover plate 3I were opened, the vapors present in the gas space above the level of the liquid within the tank would be discharged to the atmosphere, presenting a fire hazard and a loss of valuable gasoline in the form of vapors.

According to our invention, the gas collector head I2 is fitted with a gasket I3 engaging the flange l5 and the hook I engaging the opening in the projection 6 of the valve stem 5. The operating handle is then rotated to lift the valve 2 from its seat against action of the valve spring 4. This spring will then serve to hold securely the gas collector head upon flange I5. The pump 25 is then started and liquid gasoline or other suitable menstruum is pumped from reservoir 24 through pipe 26, through pump 25, through pipe 21, into the ejector device 23 which will produce, through the well known action of an ejector, a reduced pressure in pipe 22. Vapors released to the collector head I2 will be withdrawn therefrom through pipe 22 and become entrained in the liquid gasoline or other menstruum and be absorbed thereby. Liquid gasoline has the property of absorbing gasoline vapors and will hold the vapors in the liquid gasoline.

It will be noted by reference to Figure 1 that branch pipes 30 and 3| fitted with valves 32 and 33 are provided and that valves 36 and 31 are fitted at the intake and discharge ends of the pump 25. During the operation just described, valves 36 and 31 are opened and valves 32 and 33 are closed. After the tank has been gauged, the pump is stopped and the operating handle I!) is rotated to permit the spring 4 to again seat the relief valve 2. Valve 31 is closed and valve 33 is opened and the pump is again started. The gasoline in reservoir 24 is then pumped through pipe 26 through pump 2'5, through line 3|, back to the tank. When it is again desired to gauge the tank, it will be necessary to fill reservoir 24 with liquid gasoline. Just after the gas collector head is fitted and before the valve 2 is lifted from its seat, valve 36 is closed and valve 32 is opened. The pump is then started and gasoline is pumped from the tank through line 30, through line 21, into reservoir 24. If the absorption medium be any liquid other than the gasoline from which the vapors were derived, lines 30 and 3| may go to another source or tank in which the menstruum liquid is stored.

It will be obvious that we have accomplished the objects of our invention. We are enabled safely to release the vapors in a tank full of. volatile liquid on a warm day when the vapor pressure of the liquid is comparatively high, and save the loss of the vapors. In addition, in a case in which the vapors are inflammable or explosive, as with casinghead gasoline, we reduce the fire hazard.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what we claim is: I

1. In a tank for the storage of volatile liquids, a relief valve, a spring for urging said valve to seated position, a flange surrounding said valve on the exterior of said tank, a casing adapted to be seated upon said fiange, a member projecting through said casing from the exterior thereof, adapted to engage said valve, means for operating said member from the exterior of said casing to lift said valve from its seat, said casing being provided with an opening, a conduit communicating with the interior of said casing through said opening for the eduction of vapors from said casing, and means for contacting said vapors with an absorption menstruum.

2. Ina tank for the storage of volatile liquids, a relief valve, a housing for said relief valve positioned exteriorly of said tank, means operable from the exterior of said housing for lifting said relief 'valve from its seat, said housing being provided with an eduction conduit, said eduction conduit communicating with an absorption system, the construction being such that vapors released from said tank by the lifting of said valve will pass to the absorption system.

3. In a tank for the storage of volatile liquids, a relief valve, adjustable means for holding said relief valve upon its seat, a readily removable housing positioned over said valve exteriorly of said tank, a common means for holding said housing in position and lifting said relief valve from its seat.

MILLARD E. CLAWSON. FRANK MOHNK. 

